U.S. patent number 7,534,474 [Application Number 11/517,300] was granted by the patent office on 2009-05-19 for multireactive polymerizable mesogenic compounds.
This patent grant is currently assigned to Merck Patent Gesellschaft mit beschrankter Haftung. Invention is credited to David Coates, Louise Farrand.
United States Patent |
7,534,474 |
Farrand , et al. |
May 19, 2009 |
**Please see images for:
( Certificate of Correction ) ** |
Multireactive polymerizable mesogenic compounds
Abstract
The invention relates to multireactive polymerizable mesogenic
compounds of formula I R.sup.1-MG-R.sup.2 I wherein R.sup.1,
R.sup.2 and MG have the meaning given in claim 1, to a
polymerizable mesogenic composition comprising at least two
components, at least one which is a compound of formula I, to a
linear or crosslinked polymer obtainable by polymerization of one
or more compounds of formula I or of a polymerizable composition
comprising one or more compounds of formula I and to the use of a
compound of formula I, or a polymerizable composition or polymer
obtainable thereof, in optical elements such as polarizers, optical
retardation or compensation films, alignment layers, colour filters
or holographic elements, in liquid crystal displays such as PDLC,
polymer gel or polymer stabilized cholesteric texture (PSCT)
displays, in adhesives, synthetic resins with anisotropic
mechanical properties, cosmetics, diagnostics or liquid crystal
pigments, for decorative and security applications, and for
nonlinear optics or optical information storage.
Inventors: |
Farrand; Louise (Manchester,
GB), Coates; David (Dorset, GB) |
Assignee: |
Merck Patent Gesellschaft mit
beschrankter Haftung (Darmstadt, DE)
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Family
ID: |
36576393 |
Appl.
No.: |
11/517,300 |
Filed: |
September 8, 2006 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20070009675 A1 |
Jan 11, 2007 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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11059551 |
Feb 17, 2005 |
7125500 |
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09654516 |
Sep 1, 2000 |
7060200 |
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Foreign Application Priority Data
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Sep 3, 1999 [EP] |
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99116849 |
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Current U.S.
Class: |
428/1.1; 428/1.3;
252/299.67; 252/299.65; 252/299.63; 252/299.62; 252/299.61 |
Current CPC
Class: |
C09K
19/586 (20130101); C09K 19/38 (20130101); C09K
19/42 (20130101); C09K 19/0403 (20130101); C09K
19/322 (20130101); C09K 19/3405 (20130101); C09K
2323/02 (20200801); Y10T 428/10 (20150115); Y10T
428/1005 (20150115); Y10T 428/1059 (20150115); Y10T
428/1036 (20150115); Y10T 428/1041 (20150115); C09K
2019/3095 (20130101); C09K 2323/03 (20200801); C09K
2019/0444 (20130101); C09K 2019/0448 (20130101); C09K
2323/05 (20200801); C09K 2323/00 (20200801); C09K
2323/031 (20200801) |
Current International
Class: |
C09K
19/38 (20060101); C09K 19/20 (20060101); C09K
19/30 (20060101); C09K 19/32 (20060101); C09K
19/34 (20060101) |
Field of
Search: |
;252/299.01,299.5,299.61,299.62,299.63,299.65,299.67
;428/1.1,1.3 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Wu; Shean C
Attorney, Agent or Firm: Millen, White, Zelano, Branigan,
P.C.
Parent Case Text
This application is a divisional of U.S. Ser. No. 11/059,551, filed
Feb. 17, 2005 now U.S. Pat. No. 7,125,500, which is a divisional of
U.S. Ser. No. 09/654,516, filed Sep. 1, 2000, now U.S. Pat. No.
7,060,200.
Claims
The invention claimed is:
1. A multireactive polymerizable mesogenic compound of formula I
R.sup.1-MG-R.sup.2 I wherein: R.sup.1 is halogen, CN, OCN, NCS,
NO.sub.2 or an alkyl radical with 1 to 30 C atoms which may be
unsubstituted, mono- or polysubstituted by halogen or CN,
optionally one or more non-adjacent CH.sub.2 groups being replaced,
in each case independently from one another, by --O--, --S--,
--NH--, --N(CH.sub.3)--, --CO--, --COO--, --OCO--, --OCO--O--,
--S--CO--, --CO--S--, --CH.dbd.CH-- or --C.ident.C-- in such a
manner that oxygen atoms are not linked directly to one another, or
alternatively has one of the meanings of R.sup.2 or is
P-(Sp-X).sub.n--; P is a polymerizable group; Sp is a spacer group
with 1 to 25 C atoms; X is --O--, --S--, --CO--, --COO--, --OCO--,
--OCO--O--, --CO--NH--, --NH--CO--, --OCH.sub.2--, --CH.sub.2O--,
--SCH.sub.2--, --CH.sub.2S--, --CH.dbd.CH--COO--,
--OOC--CH.dbd.CH-- or a single bond; n is 0 or 1; MG is a mesogenic
group of formula VI -(A.sup.1-Z).sub.d-G-(Z-A.sup.2).sub.e- VI
wherein Z is --O--, --S--, --CO--, --COO--, --OCO--, --CO--NH--,
--NH--CO--, --CH.sub.2CH.sub.2--, --OCH.sub.2--, --CH.sub.2O--,
--SCH.sub.2--, --CH.sub.2S--, --CH.dbd.CH--, --CH.dbd.CH--COO--,
--OCO--CH.dbd.CH--, --C.ident.C-- or a single bond, A.sup.1 and
A.sup.2 are each independently 1,4-phenylene in which, in addition,
one or more CH groups are optionally replaced by N;
1,4-cyclohexylene in which, in addition, one or two non-adjacent
CH.sub.2 groups are optionally replaced by O and/or S;
1,4-cyclohexenylene; 1,4-bicyclo(2,2,2)octylene;
piperidine-1,4-diyl; naphthalene-2,6-diyl;
decahydronaphthalene-2,6-diyl; or
1,2,3,4-tetrahydro-naphthalene-2,6-diyl; all these groups
optionally being unsubstituted, mono- or polysubstituted with F,
Cl, OH, CN, NO.sub.2 or alkyl, alkoxy, alkylcarbonyl or
alkoxycarbonyl groups having 1 to 7 C atoms wherein one or more H
atoms may be substituted by F or Cl, and d and e are independently
of each other 0, 1 or 2, and G is a bivalent chiral group; and
R.sup.2 is alkyl with 1 to 25 C atoms which may be unsubstituted,
mono- or polysubstituted by halogen or CN, optionally one or more
non-adjacent CH.sub.2 groups being replaced, in each case
independently from one another, by --O--, --S--, --NH--,
--N(CH.sub.3)--, --CO--, --COO--, --OCO--, --OCO--O--, --S--CO--,
--CO--S--, --CH.dbd.CH-- or --C.ident.C-- in such a manner that
oxygen atoms are not linked directly to one another, and which is
substituted with at least two identical or different groups P.
2. The compound of claim 1, wherein P is a polymerizable group
selected from CH.sub.2.dbd.CW--COO--, WCH.dbd.CH--O--,
CH.sub.2.dbd.CH-Phenyl-(O).sub.k-- and ##STR00042## with W being H,
CH.sub.3 or Cl and k being 0 or 1.
3. The compound of claim 1, wherein G is a chiral bivalent radical
derived from a sugar, a binaphthyl compound or an optically active
glycol.
4. The compound of claim 1, wherein G is a dianhydrohexitol
group.
5. The compound of claim 1, wherein G is an ethane-1,2-diol group
substituted in 1- and/or 2-position with an alkyl or aryl group or
groups.
6. The compound of claim 1, wherein G is an optionally substituted
binaphthyl group.
7. The compound of claim 1, wherein G is a group selected from the
following groups: ##STR00043## wherein Phe is 1,4-phenylene,
R.sup.4 is F or optionally fluorinated alkyl with 1 to 4 C atoms,
and Y.sup.1, Y.sup.2, Y.sup.3 and Y.sup.4 are each independently is
halogen, CN, OCN, NCS, NO.sub.2 or an alkyl radical with 1 to 30 C
atoms which may be unsubstituted, mono- or polysubstituted by
halogen or CN, optionally one or more non-adjacent CH.sub.2 groups
being replaced, in each case independently from one another, by
--O--, --S--, --NH--, --N(CH.sub.3)--, --CO--, --COO--, --OCO--,
--OCO--O--, --S--CO--, --CO--S--, --CH.dbd.CH-- or --C.ident.C-- in
such a manner that oxygen atoms are not linked directly to one
another.
8. A compound according to claim 1, wherein R.sup.1 is not a
polymerizable group.
9. A compound according to claim 1, wherein R.sup.1 has one of the
meanings of R.sup.2.
10. A compound according to claim 1, wherein R.sup.2 is a group of
one of the following formulae:
--X-alkyl-CHP.sup.1--CH.sub.2--CH.sub.2P.sup.2 Ia
--X-alkyl-C(CH.sub.2P.sup.1)(CH.sub.2P.sup.2)--CH.sub.2P.sup.3 Ib
--X-alkyl-CHP.sup.1CHP.sup.2--CH.sub.2P.sup.3 Ic
--X-alkyl-C(CH.sub.2P.sup.1)(CH.sub.2P.sup.2)--C.sub.aH.sub.2a+1 Id
--X-alkyl-CHP.sup.1--CH.sub.2P.sup.2 Ie --X-alkyl-CHP.sup.1P.sup.2
If --X-alkyl-CP.sup.1P.sup.2--C.sub.aH.sub.2a+1 Ig
--X-alkyl-C(CH.sub.2P.sup.1)(CH.sub.2P.sup.2)--CH.sub.2OCH.sub.2--C(CH.su-
b.2P.sup.3)(CH.sub.2P.sup.4)CH.sub.2P.sup.5 Ih
--X-alkyl-CH((CH.sub.2).sub.aP.sup.1)((CH.sub.2).sub.bP.sup.2) Ii
--X-alkyl-CHP.sup.1CHP.sup.2--C.sub.aH.sub.2a+1 Ik wherein alkyl is
alkylene with 1 to 12 C atoms which may be unsubstituted, mono- or
polysubstituted by halogen or CN, one or more non-adjacent CH.sub.2
groups optionally being replaced, in each case independently from
one another, by --O--, --S--, --NH--, --N(CH.sub.3)--, --CO--,
--COO--, --OCO--, --OCO--O--, --S--CO--, --CO--S--, --CH.dbd.CH--
or --C.ident.C-- in such a manner that oxygen atoms are not linked
directly to one another, a and b are identical or different
integers from 0 to 6, X has one of the meanings given in formula I,
and P.sup.1 to P.sup.5 independently have one of the meanings of P
given in formula I.
11. A compound according to claim 1, wherein each P is
independently of each other acrylate, methacrylate, vinyl,
vinyloxy, epoxy or p-vinylphenyloxy.
12. A compound according to claim 1, wherein Sp is an alkylene
group having 1 to 20 C atoms, in which one or more non-adjacent
CH.sub.2 groups are optionally replaced by --O--, --S--, --NH--,
--N(CH.sub.3)--, --CO--, --O--CO--, --S--CO--, --O--COO--,
--CO--S--, --CO--, --CH(halogen), --CH(CN)--, --CH.dbd.CH-- or
--C.ident.C--.
13. A compound according to claim 1, wherein R.sup.1 is a chiral
alkyl radical with 1 to 30 C atoms which may be unsubstituted,
mono- or polysubstituted by halogen or CN, optionally one or more
non-adjacent CH.sub.2 groups being replaced, in each case
independently from one another, by --O--, --S--, --NH--,
--N(CH.sub.3)--, --CO--, --COO--, --OCO--, --OCO--, --S--CO--,
--CO--S--, --CH.dbd.CH-- or --C.ident.C-- in such a manner that
oxygen atoms are not linked directly to one another, provided that
sufficient C atoms and substituents or replacements are provided to
provide a chiral group.
14. A polymerizable mesogenic composition comprising at least two
components, wherein at least one component is a compound of formula
I of claim 1.
15. A linear or crosslinked polymer obtained by polymerizing a
polymerizable mesogenic compound of formula I of claim 1.
16. A linear or crosslinked polymer obtained by polymerizing a
polymerizable mesogenic composition according to claim 14.
17. A polarizer, optical retardation or compensation film,
alignment layer, colour filter, holographic element, liquid crystal
display, PDLC, polymer gel, polymer stabilized cholesteric texture
(PSCT) display, adhesive, synthetic resin with anisotropic
mechanical properties, cosmetic, diagnostic, liquid crystal pigment
for decorative and/or security applications, or article for
nonlinear optics or optical information storage comprising a
compound of the formula I of claim 1.
18. A polarizer, optical retardation or compensation film,
alignment layer, colour filter, holographic element, liquid crystal
display, PDLC, polymer gel, polymer stabilized cholesteric texture
(PSCT) display, adhesive, synthetic resin with anisotropic
mechanical properties, cosmetic, diagnostic, liquid crystal pigment
for decorative and/or security applications, or article for
nonlinear optics or optical information storage comprising a
composition according to claim 14.
19. A polarizer, optical retardation or compensation film,
alignment layer, colour filter, hologrphic element, liquid crystal
display, PDLC, polymer gel, polymer stabilized cholesteric texture
(PSCT) display, adhesive, synthetic resin with anisotropic
mechanical properties, cosmetic, diagnostic, liquid crystal pigment
for decorative and/or security applications, or article for
nonlinear optics or optical information storage comprising a
polymer according to claim 15.
Description
The invention relates to multireactive polymerizable mesogenic
compounds, to polymerizable liquid crystal compositions comprising
the multireactive compounds, to linear or crosslinked liquid
crystal polymers obtainable from the multireactive compounds and
the compositions comprising them, and to the use of the
multireactive polymerizable mesogenic compounds, the polymerizable
compositions and polymers obtained therefrom in optical elements,
liquid crystal displays, adhesives, synthetic resins with
anisotropic mechanical properties, cosmetics, diagnostics, liquid
crystal pigments, decorative and security applications, nonlinear
optics and optical information storage.
BACKGROUND OF THE INVENTION
Polymerizable mesogenic compounds, which are also known as reactive
mesogenic compounds, have been described in prior art for various
purposes. For example, they can be aligned in their liquid crystal
phase and subsequently polymerized in situ to give linear or
crosslinked liquid crystal polymer films with uniform orientation
of high quality. These films can be used for example as optical
elements, like polarization filters as described in EP 0 397 263,
broadband circular polarizers as described in EP 0 606 940 and WO
97/35219, or compensation or retardation films as described in WO
98/00475, WO 98/04651 or WO 98/12584.
For many applications it is preferred to use crosslinked polymer
films, as these show higher stability and lower temperature
dependence of the optical properties, compared to films of linear
polymers.
For this purpose, often polymerizable compositions are used which
typically comprise a mixture of direactive and monoreactive
polymerizable mesogenic compounds.
The terms reactive or polymerizable mesogenic compound as used in
the foregoing and the following comprise compounds with a
rod-shaped, lath-shaped or disk-shaped mesogenic group, i.e. a
group with the ability to induce mesophase behaviour. These
compounds do not necessarily have to exhibit mesophase behaviour by
themselves. It is also possible that these compounds show mesophase
behaviour only in mixtures with other compounds or when the
polymerizable mesogenic compounds or the mixtures comprising them
are polymerized.
A di- or multireactive compound in this connection means a compound
having a mesogenic group and two or more polymerizable terminal
groups attached to one or both sides of the mesogenic group, either
directly or via a spacer group. A monoreactive compound means a
compound having a mesogenic group, to one side of which is attached
a polymerizable terminal group, either directly or via a spacer,
and to the other side of which is attached a non-polymerizable
terminal group, like e.g. a polar group such as halogen or cyano or
a chiral or achiral alkyl or alkoxy group.
A typical example of a direactive polymerizable mesogenic compound
of the prior art is compound (A)
##STR00001## wherein R is H or CH.sub.3, which is described in EP 0
331 233 and in D. J. Broer et al., Makromol. Chem. 190, 2255-2268
(1989).
Typical examples of monoreactive polymerizable mesogenic compounds
of the prior art are compounds (B) and (C)
##STR00002## wherein R is e.g. CN or OCH.sub.3, which is described
in DE 27 22 589,
##STR00003## which is described in DE 195,04,224.
SUMMARY OF THE INVENTION
When preparing polymerizable mesogenic compositions it is possible,
by varying the ratio of mono- and direactive compounds, to control
the degree of crosslinking of the resulting polymer film, and
thereby to tune its physical and chemical properties such as the
glass transition temperature (in case of low or medium degree of
crosslinking), the temperature dependence of the optical
properties, the thermal and mechanical stability, and the stability
against organic solvents.
Furthermore, by varying the terminal group of the monoreactive
polymerizable mesogenic compound, it is possible to control the
optical properties of the polymerizable mixture and the resulting
film. For example, a helically twisted structure can be induced in
the mixture and the film by using compounds with a chiral terminal
group. Furthermore, the inventors have found that it is possible in
a polymerizable mesogenic mixture to control the orientation of the
mesogenic compounds on a substrate or on a free surface by using
compounds with polar and unpolar terminal groups in varying
ratios.
In light of what was said above, it would be desirable to have
available polymerizable mesogenic compounds that, when used in a
polymerizable mixture, allow control, at the same time of the
degree of crosslinking and the optical properties of the resulting
polymer film.
Furthermore, regarding the broad range of applications for
polymerizable mesogenic compounds it is desirable for the expert to
have available further compounds of this type which are easy to
synthesize and fulfill the various requirements as described
above.
The inventors have found that the above aims can be achieved by
providing multireactive polymerizable mesogenic compounds according
to the present invention.
The inventive compounds comprise two or more polymerizable groups
attached to the same side of a mesogenic core, whereas to the other
side of the mesogenic core there can be attached one or more
polymerizable groups or a non-polymerizable terminal group, like
e.g. a polar or unpolar group or a chiral or achiral group.
Thus, when adding multireactive compounds according to the present
invention to a polymerizable mixture, the degree of crosslinking of
the resulting polymer film is increased. At the same time it is
possible to tailor the optical properties of the mixture and the
polymer film by using an inventive multireactive compound with an
appropriately selected terminal group at its free end.
The term `free end` in this connection denotes the side of the
mesogenic group of the inventive mesogenic compounds where no
polymerizable group is attached. Thus, when using inventive
compounds in a polymerizable mixture it is possible inter alia to
control the alignment of the mixture on a substrate or on a free
surface by using inventive compounds with polar and unpolar
terminal groups at their free end in a specific ratio, to induce a
helically twisted liquid crystal phase, such as a cholesteric or
chiral phase, in the mixture by using an inventive compound with a
chiral terminal group at its free end, to increase the
birefringence of the mixture by using an inventive compound with a
highly birefringent terminal group at its free end, to increase the
dielectric anisotropy of the mixture by using an inventive compound
with a polar terminal group at its free end, while the two or more
polymerizable groups at the opposite end of the mesogenic core
contribute to the crosslinking of the polymer.
The inventive multireactive compounds wherein only one side of the
mesogenic group carries polymerizable groups, i.e. the other side
is a free end, provide an additional benefit. In a polymerized film
the free end of an inventive multireactive polymerizable compound
will not be connected to the polymer backbone, in contrast e.g. to
the direactive prior art compound (A) above, wherein both ends of
the mesogenic core will be connected to the polymer backbone. As a
consequence, the motions of the mesogenic groups of inventive
compounds are less restricted by the polymer backbone during
formation of the polymer network. This gives better alignment of
the mesogenic groups and makes it easier to achieve uniform
macroscopic orientation in a mixture comprising the inventive
compounds.
On the other hand, inventive compounds carrying two or more
polymerizable groups on each side of the mesogenic core are also
advantageous, as these compounds give more densely crosslinked
polymer networks with increased stability against heat, solvents
and mechanical stress, and wherein the uniform macroscopic
orientation is more stable. Also, in case of these compounds a
smaller amount is needed in a polymerizable mixture to obtain a
densely crosslinked film, compared e.g. to direactive compounds of
prior art, such as the above shown compound (A).
U.S. Pat. No. 5,750,213 discloses multireactive compounds of the
formula
##STR00004## wherein m is 1, 6 or 12, n is 0, 6, 7, 11, 13 or 16
and v is 0 or 1. However, the compounds disclosed in U.S. Pat. No.
5,750,213 are not substituted in p-position of the biphenyl group.
They do not show a liquid crystal phase and are liquid at room
temperature. These are serious drawbacks for the use in
polymerizable LC mixtures, since compounds without a liquid crystal
phase lower the clearing point of a liquid crystal mixture, and
liquid polymerizable compounds show increased tendency towards
spontaneous polymerization compared to solid compounds, therefore
they are less stable for storage, and increased amounts of
stabilizers are needed to prevent undesired polymerization during
storage.
One object of the present invention is multireactive polymerizable
mesogenic compounds of formula I R.sup.1-MG-R.sup.2 I wherein
R.sup.1 is halogen, CN, OCN, NCS, NO.sub.2 or a chiral or achiral
alkyl radical with 1 to 30 C atoms which may be unsubstituted,
mono- or polysubstituted by halogen or CN, it being also possible
for one or more non-adjacent CH.sub.2 groups to be replaced, in
each case independently from one another, by --O--, --S--, --NH--,
--N(CH.sub.3)--, --CO--, --COO--, --OCO--, --OCO--O--, --S--CO--,
--CO--S--, --CH.dbd.CH-- or --C.ident.C-- in such a manner that
oxygen atoms are not linked directly to one another, or
alternatively R.sup.1 has one of the meanings of R.sup.2or is
denoting P--(Sp-X).sub.n--, P is a polymerizable group, Sp is a
spacer group with 1 to 25 C atoms, X is --O--, --S--, --CO--,
--COO--, --OCO--, --OCO--O--, --CO--NH--, --NH--CO--,
--OCH.sub.2--, --CH.sub.2O--, --SCH.sub.2--, --CH.sub.2S--,
--CH.dbd.CH--COO--, --OOC--CH.dbd.CH-- or a single bond, n is 0or
1, MG is a mesogenic group, and R.sup.2 is straight-chain or
branched alkyl with 1 to 25 C atoms which may be unsubstituted,
mono- or polysubstituted by halogen or CN, it being also possible
for one or more non-adjacent CH.sub.2 groups to be replaced, in
each case independently from one another, by --O--, --S--, --NH--,
--N(CH.sub.3)--, --CO--, --COO--, --OCO--, --OCO--O--, --S--CO--,
--CO--S--, --CH.dbd.CH-- or --C.ident.C-- in such a manner that
oxygen atoms are not linked directly to one another, and which is
substituted with at least two-identical or different groups P.
Another object of the invention is a polymerizable mesogenic
composition comprising at least two components, at least one of
which is a compound of formula I.
Another object of the invention is a linear or crosslinked polymer
obtainable by polymerization of one or more compounds of formula I
or of a polymerizable composition comprising one or more compounds
of formula I.
Yet another object of the invention is the use of a compound of
formula I, or a polymerizable composition or polymer obtainable
therefrom, in optical elements such as polarizers, optical
retardation or compensation films, alignment layers, colour filters
or holographic elements, in liquid crystal displays such as PDLC,
polymer gel or polymer stabilized cholesteric texture (PSCT)
displays, in adhesives, synthetic resins with anisotropic
mechanical properties, cosmetics, diagnostics or liquid crystal
pigments, for decorative and security applications, and for
nonlinear optics or optical information storage. Upon further study
of the specification and appended claims, further objects and
advantages of this invention will become apparent to those skilled
in the art.
Particularly preferred are compounds of formula I wherein R.sup.1
is a non-polymerizable group.
Further preferred are compounds of formula I wherein R.sup.1 has
one of the meanings of R.sup.2. Of these compounds, very preferred
are those wherein R.sup.1 and R.sup.2 have the same meaning.
Further preferred are compounds of formula I wherein MG is selected
of formula II -(A.sup.1-Z).sub.m-A.sup.2- II wherein Z is in each
case independently --O--, --S--, --CO--, --COO--, --OCO--,
--CO--NH--, --NH--CO--, --CH.sub.2CH.sub.2--, --OCH.sub.2--,
--CH.sub.2O--, --SCH.sub.2--, --CH.sub.2S--, --CH.dbd.CH--,
--CH.dbd.CH--COO--, --OCO--CH.dbd.CH--, --C.ident.C-- or a single
bond, A.sup.1 and A.sup.2 are each independently 1,4-phenylene in
which, in addition, one or more CH groups may be replaced by N,
1,4-cyclohexylene in which, in addition, one or two non-adjacent
CH.sub.2 groups may be replaced by O and/or S, 1,4-cyclohexenylene,
1,4-bicyclo(2,2,2)octylene, piperidine-1,4-diyl,
naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl, or
1,2,3,4-tetrahydro-naphthalene-2,6-diyl, it being possible for all
these groups to be unsubstituted, mono- or polysubstituted with F,
Cl, OH, CN, NO.sub.2 or alkyl, alkoxy, alkylcarbonyl or
alkoxycarbonyl groups having 1 to 7 C atoms wherein one or more H
atoms may be substituted by F or Cl, and m is 1, 2 or 3.
Further preferred are compounds of formula I wherein P is selected
from CH.sub.2.dbd.CW--COO--, WCH.dbd.CH--O--,
CH.sub.2.dbd.CH-Phenyl-(O).sub.k-- and WHC--CH--, with W being H,
CH.sub.3 or Cl and k being 0 or 1.
Further preferred are compounds of formula I wherein R.sup.2 is
substituted with 2, 3, 4 or 5 identical or different polymerizable
groups P.
Particularly preferably R.sup.2 is selected from the following
subformulae --X-alkyl-CHP.sup.1--CH.sub.2--CH.sub.2P.sup.2 Ia
--X-alkyl-C(CH.sub.2P.sup.1)(CH.sub.2P.sup.2)--CH.sub.2P.sup.3 Ib
--X-alkyl-CHP.sup.1CHP.sup.2--CH.sub.2P.sup.3 Ic
--X-alkyl-C(CH.sub.2P.sup.1)(CH.sub.2P.sup.2)--C.sub.aH.sub.2a+1 Id
--X-alkyl-CHP.sup.1--CH.sub.2P.sup.2 Ie --X-alkyl-CHP.sup.1P.sup.2
If --X-alkyl-CP.sup.1P.sup.2--C.sub.aH.sub.2a+1 Ig
--X-alkyl-C(CH.sub.2P.sup.1)(CH.sub.2P.sup.2)--CH.sub.2OCH.sub.2--C(CH.su-
b.2P.sup.3)(CH.sub.2P.sup.4)CH.sub.2P.sup.5 Ih
--X-alkyl-CH((CH.sub.2).sub.aP.sup.1)((CH.sub.2).sub.bP.sup.2) Ii
--X-alkyl-CHP.sup.1CHP.sup.2--C.sub.aH.sub.2a+1 Ik wherein alkyl is
straight-chain or branched alkylene with 0 (i.e., a single bond) to
12 C atoms which may be unsubstituted, mono- or polysubstituted by
halogen or CN, it being also possible for one or more non-adjacent
CH.sub.2 groups to be replaced, in each case independently from one
another, by --O--, --S--, --NH--, --N(CH.sub.3)--, --CO--, --COO--,
--OCO--, --OCO--O--, --S--CO--, --CO--S--, --CH.dbd.CH-- or
--C.ident.C-- in such a manner that oxygen atoms are not linked
directly to one another, a and b are identical or different
integers from 0 to 6, X has one of the meanings of formula 1, and
P.sup.1 to P.sup.5 have each independently one of the meanings of P
given above.
In the above preferred subformulae alkyl is especially preferably
--(CH.sub.2).sub.c--, with c being an integer from 0 to 12.
P and P.sup.1 to P.sup.5 in formula I and the preferred subformulae
are especially preferably, independently of each other, acrylate,
methacrylate, vinyl, vinyloxy, epoxy or p-vinylphenyloxy.
A smaller group of preferred mesogenic groups of formula II is
listed below. For reasons of simplicity, Phe in these groups is
1,4-phenylene, PheL is a 1,4-phenylene group which is substituted
by 1 to 4 groups L, with L being F, Cl, CN, OH, NO.sub.2 or an
optionally fluorinated alkyl, alkoxy or alkanoyl group with 1 to 7
C atoms, and L Cyc is 1,4-cyclohexylene. The following list of
preferred mesogenic groups comprises the subformulae II-1 to II-25
as well as their mirror images -Phe-Z-Phe- II-1 -Phe-Z-Cyc- II-2
-Cyc-Z-Cyc- II-3 -PheL-Z-Phe- II-4 -PheL-Z-Cyc- II-5 -PheL-Z-PheL-
II-6 -Phe-Z-Phe-Z-Phe- II-7 -Phe-Z-Phe-Z-Cyc- II-8
-Phe-Z-Cyc-Z-Phe- II-9 -Cyc-Z-Phe-Z-Cyc- II-10 -Phe-Z-Cyc-Z-Cyc-
II-11 -Cyc-Z-Cyc-Z-Cyc- II-12 -Phe-Z-Phe-Z-PheL- II-13
-Phe-Z-PheL-Z-Phe- II-14 -PheL-Z-Phe-Z-Phe- II-15
-PheL-Z-Phe-Z-PheL- II-16 -PheL-Z-PheL-Z-Phe- II-17
-PheL-Z-PheL-Z-PheL- II-18 -Phe-Z-PheL-Z-Cyc- II-19
-Phe-Z-Cyc-Z-PheL- II-20 -Cyc-Z-Phe-Z-PheL- II-21
-PheL-Z-Cyc-Z-PheL- II-22 -PheL-Z-PheL-Z-Cyc- II-23
-PheL-Z-Cyc-Z-Cyc- II-24 -Cyc-Z-PheL-Z-Cyc- II-25
Particularly preferred are the subformulae II-1, II-2, II-4, II-6,
II-7, II-8, II-11, II-13, II-14, II-15 and II-16.
In these preferred groups Z in each case independently has one of
the meanings of Z.sup.1 as given in formula I. Preferably Z is
--COO--, --OCO--, --CH.sub.2CH.sub.2--, --C.ident.C-- or a single
bond.
Very preferably the mesogenic group MG is selected from the
following formulae and their mirror images
##STR00005##
##STR00006## wherein L has the meaning given above and r is 0, 1 or
2.
The group
##STR00007## in these preferred formulae is very preferably
denoting
##STR00008## furthermore
##STR00009## with L having each independently one of the meanings
given above.
Particularly preferred are the subformulae IId, IIg, IIh, IIi, IIk
and IIo, in particular the subformulae IId and IIk.
L is preferably F, Cl, CN, OH, NO.sub.2, CH.sub.3, C.sub.2H.sub.5,
OCH.sub.3, OC.sub.2H.sub.5, COCH.sub.3, COC.sub.2H.sub.5,
COOCH.sub.3, COOC.sub.2H.sub.5, CF.sub.3, OCF.sub.3, OCHF.sub.2,
OC.sub.2F.sub.5, in particular F, Cl, CN, CH.sub.3, C.sub.2H.sub.5,
OCH.sub.3, COCH.sub.3 and OCF.sub.3, most preferably F, Cl,
CH.sub.3, OCH.sub.3 and COCH.sub.3.
In the compounds of formula I R.sup.1 may be a polar or unpolar
group.
In case R.sup.1 is a polar group, it is preferably selected from
CN, NO.sub.2, halogen, OCH.sub.3, OCN, NCS, COR.sup.3, COOR.sup.3
or a mono-, oligo- or poly-fluorinated alkyl or alkoxy group with 1
to 4 C atoms. R.sup.3 is optionally fluorinated alkyl with 1 to 4,
preferably 1 to 3 C atoms. Halogen is preferably F or Cl.
Especially preferably R.sup.1 in these compounds is selected from
F, Cl, CN, NO.sub.2, OCH.sub.3, COCH.sub.3, COC.sub.2H.sub.5,
COOCH.sub.3, COOC.sub.2H.sub.5, CF.sub.3, C.sub.2F.sub.5,
OCF.sub.3, OCHF.sub.2, and OC.sub.2F.sub.5, in particular from F,
Cl, CN, OCH.sub.3 and OCF.sub.3.
In case R.sup.1 is an unpolar group, it is preferably alkyl with up
to 15 C atoms or alkoxy with 2 to 15 C atoms.
If R.sup.1 in formula I is an alkyl or alkoxy radical, i.e. where
the terminal CH.sub.2 group is replaced by --O--, this may be
straight-chain or branched. It is preferably straight-chain, has 2,
3, 4, 5, 6, 7 or 8 carbon atoms and accordingly is preferably
ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, ethoxy,
propoxy, butoxy, pentoxy, hexoxy, heptoxy, or octoxy, furthermore
methyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl,
pentadecyl, methoxy, nonoxy, decoxy, undecoxy, dodecoxy, tridecoxy
or tetradecoxy, for example.
Oxaalkyl, i.e. where one CH.sub.2 group is replaced by --O--, is
preferably straight-chain 2-oxapropyl (=methoxymethyl),
2-(=ethoxymethyl) or 3-oxabutyl (=2-methoxyethyl), 2-, 3-, or
4-oxapentyl, 2-, 3-, 4-, or 5-oxahexyl, 2-, 3-, 4-, 5-, or
6-oxaheptyl, 2-, 3-, 4-, 5-, 6- or 7-oxaoctyl, 2-, 3-, 4-, 5-, 6-,
7- or 8-oxanonyl or 2-, 3-, 4-, 5-, 6-,7-, 8- or 9-oxadecyl, for
example.
In the compounds of formula I R.sup.1 may be an achiral or a chiral
group. In case of a chiral group it is preferably selected
according to the following formula III:
##STR00010## wherein X.sup.1 is --O--, --S--, --CO--, --COO--,
--OCO--, --OCOO-- or a single bond, Q.sup.1 is an alkylene or
alkylene-oxy group with 1 to 10 C atoms or a single bond, Q.sup.2
is an alkyl or alkoxy group with 1 to 10 C atoms which may be
unsubstituted, mono- or polysubstituted by halogen or CN, it being
also possible for one or more non-adjacent CH.sub.2 groups to be
replaced, in each case independently from one another, by
--C.ident.C--, --O--, --S--, --NH--, --N(CH.sub.3)--, --CO--,
--COO--, --OCO--, --OCO--O--, --S--CO-- or --CO--S-- in such a
manner that oxygen atoms are not linked directly to one another,
Q.sup.3 is halogen, a cyano group or an alkyl or alkoxy group with
1 to 4 C atoms different from Q.sup.2.
In case Q.sup.1 in formula III is an alkylene-oxy group, the O atom
is preferably adjacent to the chiral C atom.
Preferred chiral groups R.sup.1 are 2-butyl (=1-methylpropyl),
2-methylbutyl, 2-methylpentyl, 3-methylpentyl, 2-ethylhexyl,
2-propylpentyl, 2-octyl, in particular 2-methylbutyl,
2-methylbutoxy, 2-methylpentoxy, 3-methylpentoxy, 2-ethylhexoxy,
1-methylhexoxy, 2-octyloxy, 2-oxa-3-methylbutyl,
3-oxa-4-methylpentyl, 4-methylhexyl, 2-nonyl, 2-decyl, 2-dodecyl,
6-methoxyoctoxy, 6-methyloctoxy, 6-methyloctanoyloxy,
5-methylheptyloxycarbonyl, 2-methylbutyryloxy, 3-methylvaleroyloxy,
4-methylhexanoyloxy, 2-chlorpropionyloxy,
2-chloro-3-methylbutyryloxy, 2-chloro-4-methylvaleryloxy,
2-chloro-3-methylvaleryloxy, 2-methyl-3-oxapentyl,
2-methyl-3-oxahexyl, 1-methoxypropyl-2-oxy, 1-ethoxypropyl-2-oxy,
1-propoxypropyl-2-oxy, 1-butoxypropyl-2-oxy, 2-fluorooctyloxy,
2-fluorodecyloxy for example.
In addition, compounds of formula I containing an achiral branched
group R.sup.1 may occasionally be of importance, for example, due
to a reduction in the tendency towards crystallization. Branched
groups of this type generally do not contain more than one chain
branch. Preferred achiral branched groups are isopropyl, isobutyl
(=methylpropyl), isopentyl (=3-methylbutyl), isopropoxy,
2-methylpropoxy and 3-methylbutoxy.
Very preferably R.sup.1 in formula I is halogen, cyano or an
optionally fluorinated achiral or chiral alkyl or alkoxy group with
1 to 15 C atoms.
Another preferred embodiment of the present invention relates to
compounds of formula I wherein R.sup.1 is denoting
P-(Sp-X).sub.n--.
P and P.sup.1 to P.sup.5 in formula I are preferably an acrylate
group, a methacrylate group, a vinyl or vinyloxy group, an epoxy
group, a styrene group or a propenyl ether group, in particular an
acrylate, methacrylate, vinyl or epoxy group.
As for the spacer group Sp in formula I all groups can be used that
are known for this purpose to the skilled in the art. The spacer
group Sp is preferably a linear or branched alkylene group having 1
to 20 C atoms, in particular 1 to 12 C atoms, in which, in
addition, one or more non-adjacent CH.sub.2 groups may be replaced
by --O--, --S--, --NH--, --N(CH.sub.3)--, --CO--, --O--CO--,
--S--CO--, --O--COO--, --CO--S--, --CO--O--, --CH(halogen)-,
--CH(CN)--, --CH.dbd.CH-- or --C.ident.C--.
Typical spacer groups are for example --(CH.sub.2).sub.o--,
--(CH.sub.2CH.sub.2O).sub.p--CH.sub.2CH.sub.2--,
--CH.sub.2CH.sub.2--S--CH.sub.2CH.sub.2-- or
--CH.sub.2CH.sub.2--NH--CH.sub.2CH.sub.2--, with o being an integer
from 2 to 12 and p being an integer from 1 to 3.
Preferred spacer groups are ethylene, propylene, butylene,
pentylene, hexylene, heptylene, octylene, nonylene, decylene,
undecylene, dodecylene, octadecylene, ethyleneoxyethylene,
methyleneoxybutylene, ethylene-thioethylene,
ethylene-N-methyliminoethylene, 1-methylalkylene, ethenylene,
propenylene and butenylene for example.
Especially preferred are inventive compounds of formula I wherein
Sp is denoting an alkyl or alkoxy group with 2 to 8 C atoms.
Straight-chain alkyl or alkoxy groups are especially preferred.
In another preferred embodiment of the invention the chiral
compounds of formula I comprise at least one spacer group Sp that
is a chiral group of the formula IV:
##STR00011## wherein Q.sup.1 and Q.sup.3 have the meanings given in
formula III, and Q.sup.4 is an alkylene or alkylene-oxy group with
1 to 10 C atoms or a single bond, being different from Q.sup.1.
In the event that R is denoting P-Sp-X--, the two spacer groups Sp
in the compounds of formula I may be identical or different.
Of the preferred compounds described above particularly preferred
are those wherein n is 1.
In another preferred embodiment of the present invention R.sup.1 is
a terminal chiral group selected from the following groups
an ethylenglycol derivative
##STR00012## wherein R.sup.4 is an alkyl radical with 1 to 12 C
atoms, a group based on citronellol,
##STR00013## a cholesteryl group, a terpenoid radical as disclosed
e.g. in WO 96/17901, preferably selected from menthyl, neomenthyl,
campheyl, pineyl, terpineyl, isolongifolyl, fenchyl, carreyl,
myrthenyl, nopyl, geraniyl, linaloyl, neryl, citronellyl and
dihydrocitronellyl, particularly preferably menthyl, a group
selected from menthone derivatives like
##STR00014## or a terminal chiral sugar derivative comprising a
mono- or dicyclic radical with pyranose or furanose rings like, for
example, a terminal group derived from the chiral sugars disclosed
in WO 95/16007.
In another preferred embodiment of the present invention the
mesogenic group MG has at least one center of chirality.
In these compounds MG is preferably selected of formula VI
-(A.sup.1-Z).sub.d-G-(Z-A.sup.2).sub.e- VI wherein A.sup.1, A.sup.2
and Z have the meaning given in formula II, d and e are
independently of each other 0, 1 or 2, and G is a bivalent chiral
group. G in these compounds is preferably a chiral bivalent radical
derived from sugars, binaphthyl derivatives, or optically active
glycols, especially ethane-1,2-diol substituted in 1- and or
2-position with alkyl or aryl groups. In case of sugar groups,
these are preferably selected from mono- and dicyclic groups
comprising pentose or hexose rings.
Particularly preferred are the following groups G
##STR00015## wherein Phe has the meaning given above, R.sup.4 is F
or optionally fluorinated alkyl with 1 to 4 C atoms and Y.sup.1,
Y.sup.2, Y.sup.3 and Y.sup.4 have one of the meanings of R.sup.1 in
formula I.
Preferably G is dianhydrohexitol like dianhydrosorbitol
##STR00016## dianhydromannitol
##STR00017## and dianhydroiditol
##STR00018## especially preferably dianhydrosorbitol, substituted
ethane diol like
##STR00019## wherein R.sup.4 is F, CH.sub.3 or CF.sub.3, or
optionally substituted binaphthyl
##STR00020## wherein Y.sup.1, Y.sup.2, Y.sup.3 and Y.sup.4 are H, F
or optionally fluorinated alkyl with 1 to 8 C atoms.
The inventive compounds of formula I can be synthesized according
to or in analogy to methods which are known per se and which are
described in standard works of organic chemistry such as, for
example, Houben-Weyl, Methoden der organischen Chemie,
Thieme-Verlag, Stuttgart. Some specific methods of preparation can
be taken from the examples.
Furthermore, compounds of formula I wherein R.sup.2 is selected of
the preferred subformulae Ia to Ik can be prepared according to or
in analogy to the reaction schemes 1 to 14 given below, followed by
attaching polymerizable groups to the terminal OH groups by
esterification or etherification according to known methods.
##STR00021##
##STR00022##
##STR00023##
##STR00024##
##STR00025##
##STR00026##
##STR00027##
##STR00028##
##STR00029##
##STR00030##
##STR00031##
##STR00032##
##STR00033##
##STR00034## wherein R is -(A.sup.1-Z).sub.m-R.sup.1, A.sup.1, Z
and m have the meanings of formula II, R.sup.1 is an
unpolymerizable polar or unpolar group as defined above, and R' is
an alkyl group with 1 to 10 C atoms.
The polymerizable groups can be attached to the terminal OH groups
as described for example in reaction scheme 15, or in analogy
thereto.
##STR00035##
An exemplary method of preparing inventive compounds wherein MG is
selected of formula II is given in reaction scheme 16 below.
##STR00036## wherein R.sup.1 is an unpolymerizable polar or unpolar
group as defined above, Z and m have the meaning of formula II, A
and B are each independently Phe, PheL or Cyc as defined above, and
L has one of the meanings given above.
The invention also relates to a polymerizable liquid crystal
composition comprising at least two polymerizable components, at
least one of which is a compound of formula I, and to linear or
crosslinked polymers prepared from the inventive compounds and
compositions.
Suitable polymerizable mesogenic compounds that can be used as
co-components of the polymerizable liquid crystal composition,
together with the inventive compounds of formula I, are disclosed
for example in WO 93/22397; EP 0,261,712; DE 195,04,224; WO
95/22586 and WO 97/00600. The compounds disclosed in these
documents, however, are to be regarded merely as examples that
shall not limit the scope of this invention.
Typical examples representing such polymerizable mesogenic
compounds are shown in the following list of compounds, which
should, however, be taken only as illustrative and is in no way
intended to restrict, but instead to explain the present
invention:
##STR00037## ##STR00038##
In the above formulae, P has one of the meanings of formula I and
its preferred meanings as mentioned above, x and y are each
independently 1 to 12, A and D are 1 ,4-phenylene or
1,4-cyclohexylene, v is 0 or 1, Z.sup.0 is --COO--, --OCO--,
--CH.sub.2CH.sub.2-- or a single bond, Y is a polar group, R.sup.0
is an unpolar alkyl or alkoxy group, Ter is a terpenoid radical
like e.g. menthyl, Chol is a cholesteryl group, and L.sup.1 and
L.sup.2 are each independently H, F, Cl, CN or an optionally
halogenated alkyl, alkoxy or carbonyl or group with 1 to 7 C
atoms.
In a preferred embodiment of the invention the polymerizable liquid
crystalline composition comprises at least one multireactive
compound of formula I and at least one mono- or direactive
polymerizable compound, i.e. a mesogenic compound having one or two
polymerizable groups. Especially preferred are monoreactive
compounds selected of formulae V4 to V15 and direactive compounds
selected of formulae V1, V2 and V3 above.
It is also possible for the inventive polymerizable liquid
crystalline composition to comprise one or more non-polymerizable
chiral compounds, which may be mesogenic or non-mesogenic, in
addition or alternatively to chiral polymerizable compounds. For
example, commercially available dopants, like e.g. S 811, R 1011 or
CB 15 (from Merck KGaA, Germany) can be used for this purpose.
Especially preferred are chiral non-polymerizable dopants with a
high helical twisting power (HTP) selected of formula VII
##STR00039## and/or formula VIII
##STR00040## including the (R,S), (S,R), (R,R) and (S,S)
enantiomers not shown, wherein E and F are each independently
1,4-phenylene or trans-1,4-cyclohexylene, v is 0 or 1, Z.sup.0 is
--COO--, --OCO--, --CH.sub.2CH.sub.2-- or a single bond, and R is
alkyl, alkoxy or alkanoyl with 1 to 12 C atoms.
The compounds of formula VII and their synthesis are described in
WO 98/00428. The compounds of formula VIII and their synthesis are
described in GB 2,328,207.
Polymerizable liquid crystalline compositions are preferred that
comprise 1 to 6, preferably 1 to 3 compounds of formula I.
In a preferred embodiment of the present invention the
polymerizable liquid crystalline composition comprises 1 to 80% by
weight, preferably 2 to 60%, in particular 5 to 50% by weight of
one or more compounds of formula I.
Particularly preferred are polymerizable compositions comprising
a1) 5 to 80%, very preferably 10 to 50% by weight of up to five,
preferably one or two compounds of formula I, a2) 5 to 90%, very
preferably 10 to 40% by weight of up to five, preferably one, two
or three monoreactive mesogenic compounds, b) 0 to 25%, very
preferably 1 to 10% by weight of a direactive polymerizable
mesogenic compound, c) 0.5 to 10%, very preferably 1 to 7% by
weight of a polymerization initiator, d) 0 to 5%, very preferably
0.1 to 2% by weight of a surfactant.
The compounds of component a2) are preferably selected from the
above formulae V4 to V15, in particular from formulae V4 to
V10.
The compounds of component b) are preferably selected from the
above formula V1 and V2.
The term polar group as used in the foregoing and the following
means a group selected from halogen, CN, NO.sub.2, OH, OCH.sub.3,
OCN, SCN, an optionally fluorinated carbonyl or carboxyl group with
up to 4 C atoms or a mono- oligo- or polyfluorinated alkyl or
alkoxy group with 1 to 4 C atoms. Especially preferred polar groups
are those as defined for Y.sup.1 in formula I, including its
preferred meanings.
The term unpolar group means an alkyl group with 1 or more,
preferably 1 to 12 C atoms or an alkoxy group with 2 or more,
preferably 2 to 12 C atoms.
Liquid crystalline polymers can be obtained from the inventive
polymerizable compounds and compositions e.g. by solution
polymerization or by in-situ polymerization.
For example, solution polymerization can be carried out in a
solvent like dichloromethane, tetrahydrofuran or toluene using AIBN
as an initiator and heating for 24 hours at 30 to 60.degree. C.
The in-situ polymerization of polymerizable liquid crystalline
compounds and compositions is described in detail by D. J. Broer et
al., Makromol. Chem. 190, 2255ff. and 3202ff. (1989).
The polymerizable liquid crystal compounds and compositions
according to this invention are preferably polymerized in situ as
described in the foregoing and the following.
The inventive compounds and polymerizable liquid crystalline
compositions are particularly useful for the preparation of
anisotropic polymer films, such as nematic or cholesteric polymer
films, with uniform molecular orientation.
Thus, another object of the invention is an anisotropic polymer
film with an oriented liquid crystalline phase that is obtainable
by polymerizing a polymerizable liquid crystalline composition
comprising at least one compound of formula I.
To prepare an anisotropic polymer film with uniform orientation, an
inventive polymerizable mesogenic composition is preferably coated
onto a substrate, aligned and polymerized in situ by exposing them
to heat or actinic radiation. Alignment and curing are preferably
carried out in the liquid crystalline phase of the composition.
Actinic radiation means irradiation with light, like UV light, IR
light or visible light, irradiation with X-rays or gamma rays or
irradiation with high energy particles, such as ions or electrons.
As a source for actinic radiation for example a single UV lamp or a
set of UV lamps can be used. Another possible source for actinic
radiation is a laser, like e.g. a UV laser, an IR laser or a
visible laser.
When polymerizing by means of UV light, for example a
photoinitiator can be used that decomposes under UV irradiation to
produce free radicals or ions that start the polymerization
reaction.
It is also possible to use a cationic photoinitiator, when curing
reactive mesogens with for example vinyl and epoxide reactive
groups, that photocures with cations instead of free radicals.
As a photoinitiator for radical polymerization for example the
commercially available Irgacure 651, Irgacure 184, Darocure 1173 or
Darocure 4205 (all from Ciba Geigy AG) can be used, whereas in case
of cationic photopolymerization the commercially available UVI 6974
(Union Carbide) can be used.
Preferably the polymerizable liquid crystalline composition
comprises 0.01 to 10%, in particular 0.05 to 8%, very preferably
0.1 to 5% by weight of a photoinitiator, especially preferably a
UV-photoinitiator.
In addition to the components mentioned above, the polymerizable
composition may also comprise one or more other suitable components
such as e.g. catalysts, stabilizers, chain-transfer agents,
co-reacting monomers or surface-active compounds. In particular the
addition of stabilizers is preferred in order to prevent undesired
spontaneous polymerization of the polymerizable material e.g.
during storage.
As stabilizers in principal all compounds can be used that are
known to the skilled in the art for this purpose. These compounds
are commercially available in a broad variety. Typical examples for
stabilizers are 4-ethoxyphenol or butylated hydroxytoluene
(BHT).
Other additives, like e.g. chain transfer agents, can also be added
to the polymerizable material in order to modify the physical
properties of the inventive polymer film. When adding a chain
transfer agent, such as monoreactive thiol compounds like e.g.
dodecane thiol or multireactive thiol compounds like e.g.
trimethylpropane tri(3-mercaptopropionate), to the polymerizable
material, the length of the free polymer chains and/or the length
of the polymer chains between two crosslinks in the inventive
polymer film can be controlled. When the amount of the chain
transfer agent is increased, the polymer chain length in the
obtained polymer film is decreasing.
It is also possible, in order to increase crosslinking of the
polymers, to add up to 20% of a non-mesogenic compound with two or
more polymerizable functional groups to the polymerizable
composition alternatively or additionally to di- or multireactive
mesogenic compounds.
Typical examples for direactive non-mesogenic monomers are
alkyldiacrylates or alkyldimethacrylates with alkyl groups of 1 to
20 C atoms. Typical examples for non mesogenic monomers with more
than two polymerizable groups are trimethylpropanetrimethacrylate
or pentaerythritoltetraacrylate.
In a preferred embodiment of the invention the polymerization of
the polymerizable composition is carried out under an atmosphere of
inert gas, preferably under a nitrogen atmosphere.
As a substrate for example a glass or quartz sheet as well as a
plastic film or sheet can be used. It is also possible to put a
second substrate on top of the coated mixture prior to, during
and/or after polymerization. The substrates can be removed after
polymerization or not. When using two substrates in case of curing
by actinic radiation, at least one substrate has to be transmissive
for the actinic radiation used for the polymerization.
Isotropic or birefringent substrates can be used. In case the
substrate is not removed from the polymerized film after
polymerization, preferably isotropic substrates are used.
Preferably at least one substrate is a plastic substrate such as
for example a film of polyester such as polyethyleneterephthalate
(PET), of polyvinylalcohol (PVA), polycarbonate (PC) or
triacetylcellulose (TAC), especially preferably a PET film or a TAC
film. As a birefringent substrate for example an uniaxially
stretched plastic film can be used. For example PET films are
commercially available from ICI Corp. under the trade name
Melinex.
In a preferred embodiment of the present invention, the inventive
polymerizable composition is coated as a thin layer on a substrate
or between two substrates and is aligned in its liquid crystal
phase to give a uniform orientation.
A uniform orientation can be achieved for example by shearing the
mixture, e.g. by means of a doctor blade. It is also possible to
apply an alignment layer, for example a layer of rubbed polyimide
or sputtered SiO.sub.x, on top of at least one of the substrates.
In some cases, the mixtures orient themselves spontaneously on the
substrate, or good alignment is achieved already by the act of
coating the mixture.
In another preferred embodiment, a second substrate is put on top
of the coated material. In this case, the shearing caused by
putting together the two substrates is sufficient to give good
alignment. It is also possible to apply electric or magnetic fields
to align the coated mixture.
The polymerizable composition according to the present invention
may also comprise one or more surfactants to improve planar
alignment. Suitable surfactants are described for example in J.
Cognard, Mol. Cryst. Liq. Cryst. 78, Supplement 1, 1-77 (1981).
Particularly preferred are non-ionic surfactants, such as the
commercially available fluorocarbon surfactants Fluorad 171 (from
3M Co.), or Zonyl FSN (from DuPont). Preferably the polymerizable
mixture comprises 0.01 to 5%, in particular 0.1 to 3%, very
preferably 0.2 to 2% by weight of surfactants.
In some cases it is of advantage to apply a second substrate not
only to aid alignment of the polymerizable mixture but also to
exclude oxygen that may inhibit the polymerization. Alternatively
the curing can be carried out under an atmosphere of inert gas.
However, curing in air is also possible using suitable
photoinitiators and high lamp power. When using a cationic
photoinitiator oxygen exclusion most often is not needed, but water
should be excluded.
For the preparation of anisotropic polymer gels, e.g. for use in
switchable liquid crystal display devices, the polymerizable
compounds or compositions can be polymerized in situ as described
above, however, in this case alignment of the polymerizable mixture
is not necessarily required, although it may be desired for
specific applications.
The invention also relates to the use of inventive compounds,
compositions and polymers such as polarizers, optical retardation
or compensation films, alignment layers, colour filters or
holographic elements, in liquid crystal displays such as PDLC,
polymer gel or polymer stabilized cholesteric texture (PSCT)
displays, in adhesives, synthetic resins with anisotropic
mechanical properties, cosmetics, diagnostics or liquid crystal
pigments, for decorative and security applications, and for
nonlinear optics or optical information storage. Inventive
compounds comprising a chiral group can also be used as chiral
dopants.
The inventive compounds of formula I are particularly suitable for
the preparation of oriented liquid crystal polymer films that can
be used as polarization or compensation films in liquid crystal
displays.
Without further elaboration, it is believed that one skilled in the
art can, using the preceding description, utilize the present
invention to its fullest extent. The following preferred specific
embodiments are, therefore, to be construed as merely illustrative,
and not limitative of the remainder of the disclosure in any way
whatsoever.
In the foregoing and in the following examples, all temperatures
are set forth uncorrected in degrees Celsius; and, unless otherwise
indicated, all parts and percentages are by weight.
The entire disclosure of all applications, patents and
publications, cited above and below, and of corresponding European
application No. 99 116 849.3, filed Sep. 3, 1999, are hereby
incorporated by reference.
EXAMPLES
Without further elaboration, it is believed that one skilled in the
art can, using the preceding description, utilize the present
invention to its fullest extent. The following examples are,
therefore, to be construed as merely illustrative and not
limitative of the remainder of the disclosure in any way
whatsoever.
In the foregoing and in the following examples, unless otherwise
indicated, all temperatures are set forth uncorrected in degrees
Celsius and all parts and percentages are by weight.
The following abbreviations are used to illustrate the liquid
crystalline phase behaviour of the compounds: K=crystalline;
N=nematic; S=smectic; Ch=cholesteric; I=isotropic. The numbers
between the symbols indicate the phase transition temperatures in
.degree. C.
Example 1
Compound (1) was prepared as follows according to reaction schemes
6 and 15.
##STR00041##
1a)
4'-Octyl-biphenyl-4-carboxylic acid (10.0 g, 32 mmol), thionyl
chloride (3.0 ml, 1.3 equiv.) and 2 drops of N-methyl pyrrolidone
were stirred under reflux in DCM (100 ml) for 2 hours. The solution
was evaporated to dryness on a rotary evaporator. The residual
brown oil which solidified on standing was used without further
purification in the next step.
1b)
Acid chloride 1a (10.5 g, 32 mmol) was added to a solution of
solketal (4.0 ml, 32 mmol) and pyridine (3.1 ml, 1.2 equiv., 38.4
mmol) in DCM (100 ml). The solution was stirred under reflux
overnight, cooled to room temperature and evaporated to dryness on
a rotary evaporator. The product was purified by flash
chromatography (4:1 petroleum ether:ethyl acetate) to leave upon
evaporation of the appropriate fractions a yellow oil which
solidified on standing. Yield 10.0 g, 95%, melting point 48.degree.
C. .sup.1H NMR showed the expected signals.
1c)
Acetal 1b (10.0 g, 23.6 mmol) was stirred in a solution of aqueous
ethanol (150 ml) in the presence of 2 ml conc. sulphuric acid for 2
hours. The solution was cooled, concentrated in vacuo, water was
added until a white solid precipitated. The solid was collected by
vaccum filtration (4.9 g, 54%). IR (nujol mull) showed a broad O--H
stretch at 3500-3200 cm.sup.-1.
The compound has a smectic phase, with K 91 S.sub.A 114 I.
1)
Diol 1c (4.8 g, 12.5 mmol), 3-chloropropionyl chloride (2.4 ml, 25
mmol) and triethylamine (10.5 ml, 75 mmol) were dissolved in DCM
(50 ml) and stirred at 35.degree. C. for 16 hours. The solution was
cooled, washed with water, dried (Na.sub.2SO.sub.4) evaporated to
dryness. The residual oil was purified by flash column
chromatography to leave an oil which crystallized on standing.
Yield 5.3 g, 88%. .sup.1H NMR gave the expected signals.
The preceding examples can be repeated with similar success by
substituting the generically or specifically described reactants
and/or operating conditions of this invention for those used in the
preceding examples.
From the foregoing description, one skilled in the art can easily
ascertain the essential characteristics of this invention and,
without departing from the spirit and scope thereof, can make
various changes and modifications of the invention to adapt it to
various usages and conditions.
* * * * *